Phylogenetic Analysis Of The Odontobutids And Population Genetic Of The Odontobutis In China

Odontobutidae is restricted to East Asia and has received little revisionary attention,even though it is an important part of gobiiform diversity.Odontobutids are distinct from the majority of gobiiforms;they are larger-bodied,less morphologically reduced and restricted to freshwater.It has recently been demonstrated that Odontobutidae + the similarly generalized Rhyacichthyidae form a clade exclusive of all other gobies,but the genera and species within Odontobutidae have not been considered.The composition of the Odontobutidae is controversial.Phylogenetic relationship among the odontobutids has never been really tested.Here,we sampled 41 specimens,representing all known genera of the Odontobutidae except the Laotian genus Terateleotris,in addition to a disputable odontobutid species,Philypnus chalmersi and 14 outgroups(6 families).We collected sequence data of 4434 single-copy nuclear coding loci using gene capture and Illumina sequencing.A robust phylogeny of the odontobutids and outgroups was built,confirming that the Odontobutidae is monophyletic and sister to the Rhyacichthyidae.We verified that Neodontobutis,Sineleotris and Philypnus chalmersi are members of the Odontobutidae based on the resulting phylogeny as well as patterns of pectoral girdle examined by X-ray microtomography.We proposed a new genus Microdous for Philypnus chalmersi based on the new morphological and molecular evidences.The family of the Odontobutidae can be divided into two clades:Microdous(=Philypnus)sister to a group consisting of Micropercops and Sineleotris,and Odontobutis sister to a group unifying Perccottus and Neodontobutis.Divergence time among the odontobutids was estimated based on 100 most clock-like loci and three fossil calibration points using BEAST.Ancestral range of the family was reconstructed using Reconstruct Ancestral States in Phylogenies(RASP)and BioGeoBEARS.The results suggested that the common ancestor of the odontobutids originated around 30 Ma in South China.Orogeny,climatic change and river capture might account for diversification and current distribution of the odontobutids.To resolve the controversies in molecular systematics of the Odontobutis,we sampled 47 specimens.Phylogenetics reconstructed on the data of thousands of nuclear coding loci confirmed that the Odontobutis is monophyletic and sister to the group unifying Neodontobutis and Perccottus.The phylogeny of species within the genus Odontobutis was that a clade consisting of Odontobutis obscura and Odontobutis hikimius was found as the most basal taxon,a clade unifying Odontobutis sinensis and Odontobutis haifengensis formed subsequently and a clade only having Odontobutis platycephala is sister to a clade consisting of Odontobutis yaluensis sister to Odontobutis potamophila and Odontobutis interrupta.The results of divergence time estimation and biogeography suggested that the common ancestor of the Odontobutis have a wide distribution among South China,the southern of the Korea Peninsula and Japan.Along with geographic isolation in these distribution areas,the odontobutids underwent evolution independently.During the glacial period,they had gene flow with each other again via the temporary freshwater connection.To evaluate their genetic diversity,the evolutionary relationship of population within 3 species of the Odontobutis in China was reconstructed based on the sequence data of thousands of single-copy nuclear gene.We found that O.potamophila,O.sinensis and O.yaluensis underwent genetic divergence.The analyses of population genetic structure were conducted by plenty of SNPs data.Results showed that O.potamophila has 3 Cluster,O.sinensis is consisting of 4 Cluster and O.yaluensis has 2 Cluster.The development of population genetic structure was revelent to the environmental change of river system,such as the width of the river,water velocity and sediment concentration.